If you filter the records so that only the "US" records show up in your view, and then add a new record, the new record won't show upbecause it's filtered out.

DataRowView drv = myDataView.AddNew();

To solve this problem, you might spend considerable effort debugging. Or maybe your immediate reaction would be to victimize the datagrid (which could possibly be the third-party component). But the reality is that the problem is with the code! Take a look:

myDataView.RowFilter = "country = 'us'",

Due to this filter, dataview would have only those rows which satisfy the condition that all other rows are not part of the view. So when a new row is added, the value of drRow["country"] is DBNull due to the fact that the new row is not part of filtered dataview.